Helicopters take off from and land at airports, as well as a multitude of off-airport sites. However, helicopters are often flown differently around airports than at other landing zones. This may be due to several reasons, including noise abatement or presence of fixed-wing air traffic.
Several avionics devices include an aural altitude callouts to indicate to the pilot the height over terrain rather than an absolute altitude over sea level. Such altitude callouts allow a helicopter pilot to properly remain either in an approved approach to a runway or within an operating height for moving along taxiways or other movement proximate to the airport or heliport. Unfortunately, air traffic communications during landing and transitioning to ground traffic include critical information. At times, these callouts will occur just when critical air traffic communication with the tower is necessary to avoid other aircraft near the airport or heliport. Where the pilot cannot hear the air traffic communication because of the aural callouts, the pilot may move the helicopter into unsafe or inappropriate positions relative to the runway or heliport.
When helicopter pilots approach to land off an airport site, the pilots generally do not need aural altitude threshold callouts at selected increments closer to the ground (such as 50, 40, 30, 20, 10). However, when they operate outside of the controlled airport space, the detailed altitude callouts closer to the ground facilitate operation such as landing at an accident scene or dusting crops.
There is an unmet need in the art for an onboard system that will generate altitude callouts and in doing so automatically or selectably alternate between suppressing and allowing a set of lower altitude threshold callout increments based upon proximity to an airport or heliport.